Friday, March 2, 2018

A Northwoods Almanac for March 2, 2018

A Northwoods Almanac for 3/2 – 3/15, 2018  

Snowy Owl Update
An estimated 280 snowy owls have been documented in Wisconsin through February 1, eclipsing the previous high of 253 tallied in 2013-14 and 240+ in 2014-15. The owls have been reported in 67 of our 72 counties, excluding only Buffalo, Florence, Forest, Menominee and Walworth. Most of the birds are now, and have been, on mid-winter territories, so any new birds are unlikely to yet arrive. Most will be departing by the end of this month while some may linger into April, with a handful of stragglers staying put into May. Mary and I fondly remember seeing a snowy owl sitting on an abandoned osprey platform at the Little Turtle Flowage on May 17, 2005, so occasionally they stay quite a while!
Wisconsin now hosts five owls tagged for research as part of Project SNOWstorm – Arlington, Austin, Badger, Bancroft, and most recently, Straubel, named after the last one caught, a juvenile female, on 2/21 at the Austin Straubel airport in Green Bay. Straubel is the 22nd owl that has been tagged by Project SNOWstorm volunteers, and the 70th since its inception.
Why are there so many snowy owls this winter? No one knows for sure, but the once held belief that large numbers of snowy owls come here in irruption years because they are all starving in Canada is erroneous. It is true that many birds arrive here in poor condition from their journey, but an almost equal number arrive in good shape. Once here, many of the birds do quite well, though some die due to collisions with vehicles, electrocution by hitting power lines, secondary rodenticide poisoning, and from illegal shooting.
The level of mortality, however, is not unexpected. Like most migratory first-year birds, juvenile raptors typically have a mortality rate near 70 percent. Juvenile songbird mortality numbers are typically even higher, demonstrating how dangerous life is for migratory birds.
Two theories suggest why we have these periodic mass movements of snowy owls. One thought, the starvation theory, is that the population of their primary northern prey source, a small rodent known as a lemming, has crashed, pushing the owls southward. More recent evidence suggests nearly the opposite, that a temporary abundance of lemmings allows the owls to successfully raise such large families that the young owls must disperse further southward to find a wintering territory. And perhaps both mechanisms play out in some years but just in different areas of Canada.
It’s hard to say what causes an irruption year because studying the population dynamics of lemmings is complex, as is studying snowy owls, since both live in very remote northern regions.

Sightings – Snowy Owl and Barred Owl
On 2/13, Rosy Richter reported seeing a snowy owl in Lac du Flambeau. She wrote, “On my drive to work from Mercer into Woodruff via Hwy. 47, I saw some crows dive-bombing something large and white just outside the tribal hatchery in Flambeau on Pokegama Lake. I pulled over, and without field glasses, it appeared to be a big white owl sitting in the snow in the middle of the bay. This was about 8:30 am.” She was quite clear that the bird had to be a snowy owl, and I have to agree with her. A snowy had been seen numerous times earlier this winter around Ike Walton Lake, which is about three miles away as the crow/owl flies, so I wonder if this wasn’t the same owl.
The question often comes up as to why crows mob owls whenever they see one. Well, one good reason is that great horned owls are known to steal nestlings at night from crows and ravens who are basically defenseless in the dark. One observer reported inspecting a crow roost that had been predated by a great horned owl. He found nine dead crows on the ground in perfect condition except that the top of their heads were gone and the brains eaten, which is a signature feeding trait of great horned owls.
Generally, however, other species of owls don’t predate crows and ravens. So, I wonder if crows simply generalize from hating great horned owls to hating all owls. Crows certainly appear to have an innate dislike of owls, and they use their flight advantage in the daylight to drive these potential predators away. I find it fascinating that numerous studies have shown crows are able to identify predators that have attempted to harm them and have the ability to share that knowledge with the rest of the flock. Thus, if owls have taken a pass at, or successfully killed any crows, the rest of the flock will likely learn about the depridations and take revenge on any owl seen.
Snowy owls aren’t known to eat crows, but since crows appear to be profiling all owls, this particular snowy just happened to be unlucky and the game was on.
Sarah Krembs in Manitowish Waters spotted a barred owl sitting close to her bird feeders in the late afteroon on 2/24. Such a sighting usually signals the barred owl is starving, given that their presence is otherwise rare around home bird feeders during the day and night.

barred owl photo by Sarah Krembs

            A barred owl’s diet varies from region to region, but here are numbers from some specific studies: In New Jersey, New York, and Connecticut, the breeding-season diet was 55% mammals, 23% invertebrates, 16% birds, 3% amphibians, and 2% fish (yes, barred owls have been observed catching fish!). In Nova Scotia, their diet was 61% mammals, 17% invertebrates, 9% birds, and 12% amphibians, reptiles, and fish. In Alberta, Canada, their diet was 46% mammals, 25% birds, 24% amphibians, and 4% invertebrates.
Winter diets are, of course, different. The winter diet in a study in Montana was 97% mammals and 3% birds.
One way or another, mammals, primarily rodents, consistently make up the largest portion of their diet.
Mary and I have seen barred owls capturing frogs on roads during a rainy night, but the importance of amphibians in a barred owl’s diet is unknown since owl pellets consisting of amphibians break up more rapidly than those made up of the bones of mammals and birds.
Migration Is ON
Birders in southern Wisconsin are reporting seeing geese by the thousands as well as hundreds of sandhill cranes, mallards, common goldeneyes, common mergansers and pintails. Red-winged blackbird flocks have also been spotted as well as the first influx of robins. Spring migration is taking off! 

Mating Mammals
            For humans, March may not feel very warm and inviting for love, but most mammals are either mating, gestating, or birthing during this period. Animals can't afford to wait to mate until the weather warms and the flowers are blooming, because their young wouldn’t be born until June or July, often too late for the growth that must happen before the young of the year face their first winter. In the squirrel family, gray squirrels have their first litter in March, while red squirrels mate in March and give birth in April.  Northern flying squirrels mate in April and give birth in May.
            Within the dog family, red foxes give birth to their kits in late March and early April, while coyotes produce young in April. Timber wolves mate in February and March and give birth in May. 
            In the weasel family, nearly all members use delayed implantation to govern their breeding cycle. Mink breed in early March and employ a short delayed implantation, giving birth in late April and early May. Striped skunks likewise breed in March, but give birth a little later in May.
            Snowshoe hares are mating, too, and chipmunks emerge seeking a partner to court, the male singing at the den entrance to entice a female. 

For several days last week, hoarfrost coated our world in ice crystals, creating a laciness on every branch and bud and needle in the woods. It’s a time of fairyland beauty that folks without winter never see.

photo by Mary Burns

 Hoarfrost is a relatively common phenomenon that requires calm winds and a supersaturated column of cold air extending well above the surface of the ground, like a cold fog. Moisture in the air starts condensing around nuclei, and once that starts, the moisture in the air “sublimates,” going directly from a gas to a solid, with ice crystals building up on everything.

Celestial Events
            With warm temperatures forecast for this weekend, get out tonight or tomorrow night for a walk in the light of the moon, which is still 99% full.
On 3/3, the area’s average high temperature reaches above freezing for the first time since 11/27.
            On 3/5, look low in the west after dusk for Mercury just one degree north of Venus. On 3/7, look in the early morning hours for Jupiter about four degrees south of the waning gibbous moon.
            March 8th shines with 11 hours and 30 minutes of daylight, and brings us to just 12 days away from the official spring equinox on 3/20.
            On 3/10, look before dawn for Saturn about two degrees south of the waning crescent moon.

Thought for the Week
“It’s a hopeful thing when scientists look to the land for knowledge, when they try to translate into mathematics the stories that water can tell. But it is not only science that we need if we are to understand. Lewis Thomas identified a fourth and highest form of language. That language is poetry. The data may change our minds, but we need poetry to change our hearts.” - Robin Wall Kimmerer

Saturday, February 17, 2018

A Northwoods Almanac for 2/16/18

A Northwoods Almanac for 2/16 – 3/1, 2018

Sightings – Northern Shrike and White-throated Sparrow
Nancy Anderson spotted a northern shrike in her yard on 2/3 and noted: “We have many common redpolls at this time here in Lac du Flambeau, so we're thinking hunting is good for this predatory song bird.” She’s right. Around one’s home, northern shrikes are a short-lived thrill to spot. While they’re uncommon and beautiful, they are there for one reason only – to scout your feeders for their next meal.

photo by Nancy Anderson

Their Latin name, Lanius excubitor, means “butcher watchman,” a fitting tribute to their skill set, because they typically sit and wait to spot prey from an exposed hunting perch. We’ve watched them sit motionless above one of our feeders for many minutes waiting for a mouse or vole to venture from a hole.
The literature says they have the ability to spot motionless birds “frozen” on branches and to capture them before they move, which is not good news for the many songbirds that utilize this defense. They’re not strong direct flyers, but they don’t give up easily, often following prey into thick bushes. They’re also known to take down birds larger than themselves, including robins, jays, and doves.
They kill birds and other vertebrates by biting the nape of the neck and “disarticulating cervical vertebrae.” Northern shrikes have bilateral, subterminal tomial teeth on their upper bill which appear to penetrate between adjacent vertebrae, quickly damaging the prey’s nerve cord, thus paralyzing and killing it.
Bilateral: both sides. Subterminal: almost at the end. Tomial: a notch on the edge of the beak. They’re not “teeth” since no bird has teeth, but they’re like a tooth along each side of the beak. These “teeth” make for a prey’s quick death, which as any hunter knows is a good thing.
There are frequent reports of shrikes killing in excess of their food requirements. Bird banders tell me of shrikes getting inside their traps and killing all the birds. But shrikes will store food, so they’re just harvesting what’s available for later use, no different than humans putting food in the refrigerator for later meals.
On another note, we have a single white-throated sparrow spending the winter at our feeders. As a ground feeder wintering in deep snow country, this white-throated sparrow has to be severely challenged to survive. I wish I could ask him why he didn’t migrate to a warmer climate with less snow back in November.
The white-throat’s winter diet is mostly grass and weed seeds, thus the need to winter further south. But they also eat fruits of sumac, grape, highbush cranberry, mountain ash, and rose hips, all of which (except sumac) we have in our yard, so perhaps that explains this lone male staying put.
 They also know how to dress for the winter – a white-throated sparrow has some 2,500 contour or body feathers in winter compared to summer's 1,500. So, the cold may not be too much of an issue for this little guy.

Update on the Clark’s Nutcracker
            Mary and I were able to visit with a very gracious couple in Oneida County who have had a Clark’s nutcracker visiting their yard since the first of the year. The nutcracker is drawn to a deer carcass they have hanging from a tree, as for that matter are chickadees, nuthatches, and other birds – fat equals high energy in a cold winter.

photo by John Bates

            As I wrote about in my last column, the nutcracker is a very rare visitor to Wisconsin, so this is a big deal in the birding world. The question that always arises when a bird is so far from its normal range is what will happen in the spring? Will the nutcracker know how to migrate back to its normal Rocky Mountain breeding habitat, or will it look around and say “What now?”
One day it will disappear from its winter restaurant, and unless banded and recovered, we’ll never know the end to the story.

Great Backyard Bird Count
The 21st Great Backyard Bird Count (GBBC) will take place February 16 to 19. This global event provides an opportunity for bird enthusiasts to contribute important bird population data to scientists so they can record changes over time. To participate, bird watchers count the birds they see for at least 15 minutes on one or more days of the count, then enter their checklists at
Over its 3-decade history, the GBBC has expanded from a 2-country count (U.S. and Canada) to a global event. During the first GBBC in 1998, bird watchers submitted about 13,500 checklists from the United States and Canada. Twenty years later in 2017, an estimated 240,418 bird watchers from more than 100 countries submitted 181,606 bird checklists and reported 6,259 species – more than half the known bird species in the world. 
The rules are easy:
Count birds for at least 15 minutes on any of the days or all: Feb 16, 17, 18, or 19.
Keep track of how long you counted and if you’re walking, how far you walked.
Go to your favorite spot or any spot. It doesn’t have to be a backyard – it can be anywhere.
Start a new count for each new place or time.
Enter your checklists at
This can be as easy as you want it to be – lots of folks simply look out their windows and count their feeders from the warmth of their homes. And in the Northwoods in February, you’re likely to see more birds that way than taking a walk or driving around looking for birds. Our Christmas bird counts have proven this many times over. Please consider joining the count!

Nesting Has Begun!
            As hard as it may be to believe, several bird species should now be nesting. Both great horned owls and gray jays are known to be incubating eggs by late February. Gray Jays nest during late winter in cold, snowy, and apparently foodless conditions, with eggs incubated at temperatures as low as -22°F. Nest building can begin in February, with clutches initiated as early as Feb 22 in Algonquin Park, Ontario, which is almost exactly the latitude of Minocqua. Interestingly, second broods or replacement nests are not attempted in May or June, the breeding period used by other boreal passerines. Gray jay nestlings are being fed before 80% of our migratory birds have even returned.
For great horned owls, females are able to maintain their eggs at incubating temperatures near 98°F, even when the ambient temperature is more than 70° colder. They’re able to incubate eggs successfully when outside temperatures are below -27°F. In one study, the eggs withstood the absence of the incubating female for 20 minutes  at -13°F when the female joined her mate hooting at a neighboring male.

Winter Birdbaths
I was asked whether winter bird baths are a good idea or not. It’s been said that birds can get their feet wet in these baths, and then freeze to the metal rods on bird feeders. I have heard of this occurring on two occasions over the last 25 years, but that’s a pretty small percentage. My sense is that the advantages far outweigh the risks. After all, birds can get their feet wet in a host of other ways in the winter – we do have open water in many creeks, and dripping icicles are common drinking sites for birds – so, bird baths are not exposing birds to some novel occurrence.
The simplest way to provide water in winter is to set out a very shallow plastic pan at the same time each day, and bring it in when ice forms. If you want to keep a birdbath ice-free, some birdbaths come with built-in, thermostatically controlled heaters.
Some simple, common sense rules include never adding antifreeze to the birdbath – it’s poisonous to all animals. Don’t use a sugar solution, either: it can saturate and matt a bird’s feathers leaving it susceptible to hypothermia. Just use plain water.
It’s also important to change the water every day or two. Bathing birds may leave behind dirty feathers and droppings, making the bath increasingly unsanitary for other birds.

Celestial Events
            The new moon occurred yesterday, 2/15. Check the night sky tonight because this is the time of year when the brightest accumulation of stars can be seen annually. Look for constellations like Orion, Sirius, Gemini, Auriga, and Taurus, all of which contain first-magnitude stars.
            Venus rises before dawn late in the month in the southwest, and will climb higher and higher as the spring returns. For right now, however, the morning planets are Saturn, Mars, and Jupiter, all of which can be seen in the southeast before dawn.
            As of 2/27, we will be receiving over 11 hours of sunlight – hooray! It’s getting lighter every day.
            February has no full moon this year. The next full moon occurs on March 1, and like January, March will have two full moons, the second one occurring on 3/31.

Thought for the Week
            “We ourselves seldom comprehend the moment at hand. So, we turn to history, the one element of our lives it is possible to fix on. Or we turn to principle. Or we turn to nature. There we find, amid the silence and mystery, order and structure, the sense that life is not simply random.”Paul Gruchow